I think they would easily get a 40B valuation on an IPO.

People know that ARM is used in all smartphones and after Apples M1 and the growing usage in Servers many believe that ARM is the future.

Also - with an IPO, customers of ARM like Apple could easily buy shares of ARM...

Probably the reason why Apple didn't bought ARM is because they know they wouldn't get through the competition authorities.

But with an IPO, Apple and other customers could buy something like 9 percent of ARM...

M1 is arm instructions apple design.

This still requires a fairly pricey license from Arm to use the ISA

Apple helped found ARM, I would be very surprised if they didn’t receive favourable terms on an eternal license.

They could also simply hire the ARM employees for a lot less than $40B over the near future.

That doesn't really help them all that much, at least not for the reasons why owning ARM could be useful: the IP.

My understanding was that Apple already reimplemented large parts of the IP and that they are now mostly a licensee of the ISA.

Apple's ISA can become more and more divergent from Arm and it wouldn't matter. Apple controls the entire software stack that runs on their hardware.

I think Apple is bound by contract to respect the original ISA (except perhaps the parts they use internally and don't expose external developers to). Forcing external parties to use a translator instead of machine language directly could be one approach to circumvent this.

Also, is not the whole value in using Arm ISA, the ecosystem behind it? If Apple starts diverging from the standard, then it cannot benefit from the existing ecosystem and neither can a software dev say develop on Mac and deploy to graviton. I think it is big lose lose if Apple diverges from standard.

Apple never used any 64-bit cores from Arm. Their own Cyclone was developed in parallel with Arm's Cortex-A57.

I mean it was valued pretty close to that on the public markets before SoftBank bought it, and tech shares in general have appreciated massively since then, so I think they could get a decent price at IPO.

That is my intuition too; ARM is a wellknown name and semiconductors is a hot sector at the moment, in particular with a shift away from X86 for personal computing.

However they probably cannot sell all the shares at an IPO and get the full 40B in cash which maybe is what SoftBank wants at present.

You must have not seen the trajectory equities are on now days. 40b would be an absolute joke to achieve by end of year.